// in cac so nguyen to trong pham vi n
#include<stdio.h>
#include<conio.h>
#include<math.h>
int ktnguyento(int );
int main(){
                int n;
                printf("nhap n: ");
                scanf("%d",&n);
                ktnguyento(n);
              for(int i=1;i<=n;i++){
                if(ktnguyento(i)==1)
                printf("%d\t",i); 
                }
                 getch();
}
int ktnguyento(int n){
    
    int dem=0;
    for(int i=1;i<=n;i++){
            if(n%i==0)
            dem++;            
    }
    return (dem == 2);
 }
